This proposal requests continued support of a program of research on children with profound hearing impairments. The long-term goal of this project is to obtain a better understanding of the benefits derived from multichannel cochlear implants (CIs) and from conventional amplification (HA). In particular, we are interested in the effects of cochlear implants on the development of speech perception, spoken word recognition, and language skills, as well as the influence of audition on selective attention. The proposed research involves extensions of our earlier comparisons of sensory aids in deaf children. First, we propose to examine the effects of age at implantation on speech and language development. Second, we plan to compare the performance of children with CIs to children with HAs, to assess the benefits obtained from CIs by children with different degrees of hearing loss. Third, we will compare CI processor strategies, specifically waveform representation vs feature extraction. Fourth, we will continue our earlier research on the effects of audition on visual attention. Finally, we propose to study exceptional users of CIs to learn more about the sensory and perceptual mechanisms that underlie their superior performance on traditional speech perception tests. Taken together the findings from this project will provide new information concerning audiological criteria for CI candidacy. The results will also provide information concerning the efficacy of new CI processor strategies in facilitating perceptual development, specifically, speech perception, language development, and selective attention, in children with profound hearing impairments.